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Full Discussion: Pointer confusion
Top Forums Programming Pointer confusion Post 302888643 by dragonpoint on Sunday 16th of February 2014 10:50:06 AM
Old 02-16-2014
Pointer confusion
Here are two programs that pass a pointer to a variable but behave differently. Shouldnt the i in second program be 0 after the function call?

Code:
#include<stdio.h>

void changeI(int *i)
{
 *i = 10;
}

int main(void)
{
 int i=5;
 printf("%d before\n", i);
 changeI(&i);
 printf("%d after\n", i);
 return 0;
}

Code:
chlsvnc01> ./temp
5 before
10 after

Code:
chlsvnc01> cat prttst3.c
#include<stdio.h>

void copy_array(int * destArray, int * srcArray, int *i)
{
 while(*i)
 {
  *destArray++ = *srcArray++;
  *i--;
 }
 printf("%d is after copy\n", *i);
 return ;
}

int main (void)
{
 int i=30;
 int s[30] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29};
 int d[30];

 printf("i before = %d\n",i);
 copy_array(d,s,&i);
 printf("i after = %d\n",i);

 for(i=0;i<30;i++)
  printf("%d\t",d[i]);
 printf("\n");
 return 0;
}

Code:
chlsvnc01> ./prttst3
i before = 30
0 is after copy
i after = 30
0       1       2       3       4       5       6       7       8       9       10      11      12      13      14      15      16      17      18      19      20      21      22      23      24      25      26      27      28      29

Last edited by bartus11; 02-16-2014 at 12:02 PM.. Reason: Please use [code][/code] tags.
 

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LEARN ABOUT OPENSOLARIS

scrl

scrl(3XCURSES)						  X/Open Curses Library Functions					    scrl(3XCURSES)

NAME

       scrl, scroll, wscrl - scroll a window

SYNOPSIS

       cc [ flag... ] file... -I /usr/xpg4/include  -L	/usr/xpg4/lib 
	-R  /usr/xpg4/lib  -lcurses  [ library... ]

       c89 [ flag... ] file... -lcurses [ library... ]

       #include <curses.h>

       int scrl(int n);

       int scroll(WINDOW *win);

       int wscrl(WINDOW *win, int n);

PARAMETERS

       n      number and direction of lines to scroll

       win    pointer to the window in which to scroll

DESCRIPTION

       The scroll() function scrolls the window win up one line.  The current cursor position is not changed.

       The  scrl() and wscrl() functions scroll the window stdscr or win up or down n lines, where n is a positive (scroll up) or negative (scroll
       down) integer.

       The scrollok(3XCURSES) function must be enabled for these functions to work.

RETURN VALUES

       On success, these functions return OK. Otherwise, they return ERR.

ERRORS

       None.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Unsafe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       clearok(3XCURSES), libcurses(3XCURSES), attributes(5), standards(5)

SunOS 5.11							    5 Jun 2002							    scrl(3XCURSES)
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